In one project, Reyes collected guns in the city of Culiacán, which had the highest rate of gun deaths in the country, and then smashed them with a steamroller, melted them down, and turned them into 1,527 shovels for planting trees.

After six years, that project is almost complete--Reyes plans to plant 1,527 trees, one for every gun that was destroyed. The plantings are happening all over the world; one week, in Costa Rica, and the next week, in Germany.

In two other projects, Reyes transformed guns into musical instruments to show a literal example of how people might express anger in a different way. "Rock and roll gives a certain degree of catharsis," he says. "Turning a machine gun into an electric guitar is a kind of transformation where you can still have a totemic object of power--an electric guitar has that kind of magical power."

I like the idea of expressing anger a different way. 

Here's one set of instruments in action, in a video from Vice:

While the artist doesn't expect violence to ever disappear, he hopes the art helps remind people of alternatives. "I think there's a reason why guns produce such a thrill," he says. "We're not much different from apes in that we have inherited a brain structure that gets excited by violence...I think violence is part of our nature, but the evolution is that we can express it towards objects instead of people."

He also hopes to slowly begin to shift cultural acceptance of guns. "It's almost a kind of impossible idea that you could turn around that perception," Reyes says. "But it's a kind of a cultural battle, and I hope art can be one little contribution to that cultural change. There were things that were normal 50 years ago, like overt racism or discrimination against gay people, that we have seen start to change in our lifetime. I believe we should also change our perception of guns."

Related:  Peter Thum has now turned 35,000 assault weapons into designer jewelry

http://upstart.bizjournals.com/entrepreneurs/hot-shots/2014/07/21/peter-thum-has-now-turned-35-000-assault-weapons.html?page=all

I guess that's one way to get guns off the street.